Role of layered double hydroxide (LDH) in the protection of herring testis DNA from heavy metals

• 1、Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, College of Environmental Science and Engineering, South China University of Technology , Guangzhou 510006, China

Abstract：The role of layered double hydroxide (LDH) in the protection of herring testis DNA from heavy metals Cd2+and Pb2+ was researched using X-ray diffraction(XRD)spectra，Fourier transform infrared(FTIR)spectra，Scanning Electron Microscopy(SEM)，Cyclic Voltammetry and Ultraviolet Spectral method．Size expansion of the basal spacing (003) from 0.76nm in LDH to 2.30 nm was observed in the resulting DNA-LDH nanohybrids and it gave peaks corresponding to C=O (1534 cm and 1488 cm1), C-O (1228 cm1), and P-O (1096 cm1) functional groups of DNA, indicating that DNA were intercalated into the LDH by the ion exchange. However, the displacement of NO3 was not fully complete (partial intercalation of DNA).Those DNA failed to insert layer was absorbed on the surface of LDH. Moreover, DNA in the composites exhibited a very similar peaks, which is corresponding to the two reduction current peaks (Ep=－1.2 mV and Ep=－2.4 mV) of free DNA. Also there wasn't cathode sag in cyclic voltammetry curve, suggesting that both Cd2 +and Pb2 + cannot insert DNA groove to associate with base pairs or other groups when DNA was bound on LDH. The results showed that, on the one hand, both Cd2 +and Pb2+ were absorbed on the external surface of LDH for immobilization , on the other hand, the layer of LDH provided ideal space for DNA by the action of protecting DNA molecules from Cd2 +and Pb2+.

Keywords： DNA-LDH nanohybrids Electrochemistry method intercalation groove binding configuration